dm-crypt.c

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/*
 * Copyright (C) 2003 Christophe Saout <[email protected]>
 * Copyright (C) 2004 Clemens Fruhwirth <[email protected]>
 * Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the GPL.
 */

#include <linux/completion.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/mempool.h>
#include <linux/slab.h>
#include <linux/crypto.h>
#include <linux/workqueue.h>
#include <linux/backing-dev.h>
#include <linux/percpu.h>
#include <linux/atomic.h>
#include <linux/scatterlist.h>
#include <asm/page.h>
#include <asm/unaligned.h>
#include <crypto/hash.h>
#include <crypto/md5.h>
#include <crypto/algapi.h>

#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "crypt"

/*
 * context holding the current state of a multi-part conversion
 */
struct convert_context {
    struct completion restart;
    struct bio *bio_in;
    struct bio *bio_out;
    unsigned int offset_in;
    unsigned int offset_out;
    unsigned int idx_in;
    unsigned int idx_out;
    sector_t cc_sector;
    atomic_t cc_pending;
};

/*
 * per bio private data
 */
struct dm_crypt_io {
    struct crypt_config *cc;
    struct bio *base_bio;
    struct work_struct work;

    struct convert_context ctx;

    atomic_t io_pending;
    int error;
    sector_t sector;
    struct dm_crypt_io *base_io;
};

struct dm_crypt_request {
    struct convert_context *ctx;
    struct scatterlist sg_in;
    struct scatterlist sg_out;
    sector_t iv_sector;
};

struct crypt_config;

struct crypt_iv_operations {
    int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
           const char *opts);
    void (*dtr)(struct crypt_config *cc);
    int (*init)(struct crypt_config *cc);
    int (*wipe)(struct crypt_config *cc);
    int (*generator)(struct crypt_config *cc, u8 *iv,
             struct dm_crypt_request *dmreq);
    int (*post)(struct crypt_config *cc, u8 *iv,
            struct dm_crypt_request *dmreq);
};

struct iv_essiv_private {
    struct crypto_hash *hash_tfm;
    u8 *salt;
};

struct iv_benbi_private {
    int shift;
};

#define LMK_SEED_SIZE 64 /* hash + 0 */
struct iv_lmk_private {
    struct crypto_shash *hash_tfm;
    u8 *seed;
};

/*
 * Crypt: maps a linear range of a block device
 * and encrypts / decrypts at the same time.
 */
enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };

/*
 * Duplicated per-CPU state for cipher.
 */
struct crypt_cpu {
    struct ablkcipher_request *req;
};

/*
 * The fields in here must be read only after initialization,
 * changing state should be in crypt_cpu.
 */
struct crypt_config {
    struct dm_dev *dev;
    sector_t start;

    /*
     * pool for per bio private data, crypto requests and
     * encryption requeusts/buffer pages
     */
    mempool_t *io_pool;
    mempool_t *req_pool;
    mempool_t *page_pool;
    struct bio_set *bs;

    struct workqueue_struct *io_queue;
    struct workqueue_struct *crypt_queue;

    char *cipher;
    char *cipher_string;

    struct crypt_iv_operations *iv_gen_ops;
    union {
        struct iv_essiv_private essiv;
        struct iv_benbi_private benbi;
        struct iv_lmk_private lmk;
    } iv_gen_private;
    sector_t iv_offset;
    unsigned int iv_size;

    /*
     * Duplicated per cpu state. Access through
     * per_cpu_ptr() only.
     */
    struct crypt_cpu __percpu *cpu;

    /* ESSIV: struct crypto_cipher *essiv_tfm */
    void *iv_private;
    struct crypto_ablkcipher **tfms;
    unsigned tfms_count;

    /*
     * Layout of each crypto request:
     *
     *   struct ablkcipher_request
     *      context
     *      padding
     *   struct dm_crypt_request
     *      padding
     *   IV
     *
     * The padding is added so that dm_crypt_request and the IV are
     * correctly aligned.
     */
    unsigned int dmreq_start;

    unsigned long flags;
    unsigned int key_size;
    unsigned int key_parts;
    u8 key[0];
};

#define MIN_IOS        16
#define MIN_POOL_PAGES 32

static struct kmem_cache *_crypt_io_pool;

static void clone_init(struct dm_crypt_io *, struct bio *);
static void kcryptd_queue_crypt(struct dm_crypt_io *io);
static u8 *iv_of_dmreq(struct crypt_config *cc, struct dm_crypt_request *dmreq);

static struct crypt_cpu *this_crypt_config(struct crypt_config *cc)
{
    return this_cpu_ptr(cc->cpu);
}

/*
 * Use this to access cipher attributes that are the same for each CPU.
 */
static struct crypto_ablkcipher *any_tfm(struct crypt_config *cc)
{
    return cc->tfms[0];
}

/*
 * Different IV generation algorithms:
 *
 * plain: the initial vector is the 32-bit little-endian version of the sector
 *        number, padded with zeros if necessary.
 *
 * plain64: the initial vector is the 64-bit little-endian version of the sector
 *        number, padded with zeros if necessary.
 *
 * essiv: "encrypted sector|salt initial vector", the sector number is
 *        encrypted with the bulk cipher using a salt as key. The salt
 *        should be derived from the bulk cipher's key via hashing.
 *
 * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 *        (needed for LRW-32-AES and possible other narrow block modes)
 *
 * null: the initial vector is always zero.  Provides compatibility with
 *       obsolete loop_fish2 devices.  Do not use for new devices.
 *
 * lmk:  Compatible implementation of the block chaining mode used
 *       by the Loop-AES block device encryption system
 *       designed by Jari Ruusu. See http://loop-aes.sourceforge.net/
 *       It operates on full 512 byte sectors and uses CBC
 *       with an IV derived from the sector number, the data and
 *       optionally extra IV seed.
 *       This means that after decryption the first block
 *       of sector must be tweaked according to decrypted data.
 *       Loop-AES can use three encryption schemes:
 *         version 1: is plain aes-cbc mode
 *         version 2: uses 64 multikey scheme with lmk IV generator
 *         version 3: the same as version 2 with additional IV seed
 *                   (it uses 65 keys, last key is used as IV seed)
 *
 * plumb: unimplemented, see:
 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 */

static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv,
                  struct dm_crypt_request *dmreq)
{
    memset(iv, 0, cc->iv_size);
    *(__le32 *)iv = cpu_to_le32(dmreq->iv_sector & 0xffffffff);

    return 0;
}

static int crypt_iv_plain64_gen(struct crypt_config *cc, u8 *iv,
                struct dm_crypt_request *dmreq)
{
    memset(iv, 0, cc->iv_size);
    *(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);

    return 0;
}

/* Initialise ESSIV - compute salt but no local memory allocations */
static int crypt_iv_essiv_init(struct crypt_config *cc)
{
    struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
    struct hash_desc desc;
    struct scatterlist sg;
    struct crypto_cipher *essiv_tfm;
    int err;

    sg_init_one(&sg, cc->key, cc->key_size);
    desc.tfm = essiv->hash_tfm;
    desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;

    err = crypto_hash_digest(&desc, &sg, cc->key_size, essiv->salt);
    if (err)
        return err;

    essiv_tfm = cc->iv_private;

    err = crypto_cipher_setkey(essiv_tfm, essiv->salt,
                crypto_hash_digestsize(essiv->hash_tfm));
    if (err)
        return err;

    return 0;
}

/* Wipe salt and reset key derived from volume key */
static int crypt_iv_essiv_wipe(struct crypt_config *cc)
{
    struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
    unsigned salt_size = crypto_hash_digestsize(essiv->hash_tfm);
    struct crypto_cipher *essiv_tfm;
    int r, err = 0;

    memset(essiv->salt, 0, salt_size);

    essiv_tfm = cc->iv_private;
    r = crypto_cipher_setkey(essiv_tfm, essiv->salt, salt_size);
    if (r)
        err = r;

    return err;
}

/* Set up per cpu cipher state */
static struct crypto_cipher *setup_essiv_cpu(struct crypt_config *cc,
                         struct dm_target *ti,
                         u8 *salt, unsigned saltsize)
{
    struct crypto_cipher *essiv_tfm;
    int err;

    /* Setup the essiv_tfm with the given salt */
    essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(essiv_tfm)) {
        ti->error = "Error allocating crypto tfm for ESSIV";
        return essiv_tfm;
    }

    if (crypto_cipher_blocksize(essiv_tfm) !=
        crypto_ablkcipher_ivsize(any_tfm(cc))) {
        ti->error = "Block size of ESSIV cipher does "
                "not match IV size of block cipher";
        crypto_free_cipher(essiv_tfm);
        return ERR_PTR(-EINVAL);
    }

    err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
    if (err) {
        ti->error = "Failed to set key for ESSIV cipher";
        crypto_free_cipher(essiv_tfm);
        return ERR_PTR(err);
    }

    return essiv_tfm;
}

static void crypt_iv_essiv_dtr(struct crypt_config *cc)
{
    struct crypto_cipher *essiv_tfm;
    struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;

    crypto_free_hash(essiv->hash_tfm);
    essiv->hash_tfm = NULL;

    kzfree(essiv->salt);
    essiv->salt = NULL;

    essiv_tfm = cc->iv_private;

    if (essiv_tfm)
        crypto_free_cipher(essiv_tfm);

    cc->iv_private = NULL;
}

static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
                  const char *opts)
{
    struct crypto_cipher *essiv_tfm = NULL;
    struct crypto_hash *hash_tfm = NULL;
    u8 *salt = NULL;
    int err;

    if (!opts) {
        ti->error = "Digest algorithm missing for ESSIV mode";
        return -EINVAL;
    }

    /* Allocate hash algorithm */
    hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(hash_tfm)) {
        ti->error = "Error initializing ESSIV hash";
        err = PTR_ERR(hash_tfm);
        goto bad;
    }

    salt = kzalloc(crypto_hash_digestsize(hash_tfm), GFP_KERNEL);
    if (!salt) {
        ti->error = "Error kmallocing salt storage in ESSIV";
        err = -ENOMEM;
        goto bad;
    }

    cc->iv_gen_private.essiv.salt = salt;
    cc->iv_gen_private.essiv.hash_tfm = hash_tfm;

    essiv_tfm = setup_essiv_cpu(cc, ti, salt,
                crypto_hash_digestsize(hash_tfm));
    if (IS_ERR(essiv_tfm)) {
        crypt_iv_essiv_dtr(cc);
        return PTR_ERR(essiv_tfm);
    }
    cc->iv_private = essiv_tfm;

    return 0;

bad:
    if (hash_tfm && !IS_ERR(hash_tfm))
        crypto_free_hash(hash_tfm);
    kfree(salt);
    return err;
}

static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv,
                  struct dm_crypt_request *dmreq)
{
    struct crypto_cipher *essiv_tfm = cc->iv_private;

    memset(iv, 0, cc->iv_size);
    *(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);
    crypto_cipher_encrypt_one(essiv_tfm, iv, iv);

    return 0;
}

static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
                  const char *opts)
{
    unsigned bs = crypto_ablkcipher_blocksize(any_tfm(cc));
    int log = ilog2(bs);

    /* we need to calculate how far we must shift the sector count
     * to get the cipher block count, we use this shift in _gen */

    if (1 << log != bs) {
        ti->error = "cypher blocksize is not a power of 2";
        return -EINVAL;
    }

    if (log > 9) {
        ti->error = "cypher blocksize is > 512";
        return -EINVAL;
    }

    cc->iv_gen_private.benbi.shift = 9 - log;

    return 0;
}

static void crypt_iv_benbi_dtr(struct crypt_config *cc)
{
}

static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv,
                  struct dm_crypt_request *dmreq)
{
    __be64 val;

    memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */

    val = cpu_to_be64(((u64)dmreq->iv_sector << cc->iv_gen_private.benbi.shift) + 1);
    put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));

    return 0;
}

static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv,
                 struct dm_crypt_request *dmreq)
{
    memset(iv, 0, cc->iv_size);

    return 0;
}

static void crypt_iv_lmk_dtr(struct crypt_config *cc)
{
    struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

    if (lmk->hash_tfm && !IS_ERR(lmk->hash_tfm))
        crypto_free_shash(lmk->hash_tfm);
    lmk->hash_tfm = NULL;

    kzfree(lmk->seed);
    lmk->seed = NULL;
}

static int crypt_iv_lmk_ctr(struct crypt_config *cc, struct dm_target *ti,
                const char *opts)
{
    struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

    lmk->hash_tfm = crypto_alloc_shash("md5", 0, 0);
    if (IS_ERR(lmk->hash_tfm)) {
        ti->error = "Error initializing LMK hash";
        return PTR_ERR(lmk->hash_tfm);
    }

    /* No seed in LMK version 2 */
    if (cc->key_parts == cc->tfms_count) {
        lmk->seed = NULL;
        return 0;
    }

    lmk->seed = kzalloc(LMK_SEED_SIZE, GFP_KERNEL);
    if (!lmk->seed) {
        crypt_iv_lmk_dtr(cc);
        ti->error = "Error kmallocing seed storage in LMK";
        return -ENOMEM;
    }

    return 0;
}

static int crypt_iv_lmk_init(struct crypt_config *cc)
{
    struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
    int subkey_size = cc->key_size / cc->key_parts;

    /* LMK seed is on the position of LMK_KEYS + 1 key */
    if (lmk->seed)
        memcpy(lmk->seed, cc->key + (cc->tfms_count * subkey_size),
               crypto_shash_digestsize(lmk->hash_tfm));

    return 0;
}

static int crypt_iv_lmk_wipe(struct crypt_config *cc)
{
    struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

    if (lmk->seed)
        memset(lmk->seed, 0, LMK_SEED_SIZE);

    return 0;
}

static int crypt_iv_lmk_one(struct crypt_config *cc, u8 *iv,
                struct dm_crypt_request *dmreq,
                u8 *data)
{
    struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
    struct {
        struct shash_desc desc;
        char ctx[crypto_shash_descsize(lmk->hash_tfm)];
    } sdesc;
    struct md5_state md5state;
    u32 buf[4];
    int i, r;

    sdesc.desc.tfm = lmk->hash_tfm;
    sdesc.desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;

    r = crypto_shash_init(&sdesc.desc);
    if (r)
        return r;

    if (lmk->seed) {
        r = crypto_shash_update(&sdesc.desc, lmk->seed, LMK_SEED_SIZE);
        if (r)
            return r;
    }

    /* Sector is always 512B, block size 16, add data of blocks 1-31 */
    r = crypto_shash_update(&sdesc.desc, data + 16, 16 * 31);
    if (r)
        return r;

    /* Sector is cropped to 56 bits here */
    buf[0] = cpu_to_le32(dmreq->iv_sector & 0xFFFFFFFF);
    buf[1] = cpu_to_le32((((u64)dmreq->iv_sector >> 32) & 0x00FFFFFF) | 0x80000000);
    buf[2] = cpu_to_le32(4024);
    buf[3] = 0;
    r = crypto_shash_update(&sdesc.desc, (u8 *)buf, sizeof(buf));
    if (r)
        return r;

    /* No MD5 padding here */
    r = crypto_shash_export(&sdesc.desc, &md5state);
    if (r)
        return r;

    for (i = 0; i < MD5_HASH_WORDS; i++)
        __cpu_to_le32s(&md5state.hash[i]);
    memcpy(iv, &md5state.hash, cc->iv_size);

    return 0;
}

static int crypt_iv_lmk_gen(struct crypt_config *cc, u8 *iv,
                struct dm_crypt_request *dmreq)
{
    u8 *src;
    int r = 0;

    if (bio_data_dir(dmreq->ctx->bio_in) == WRITE) {
        src = kmap_atomic(sg_page(&dmreq->sg_in));
        r = crypt_iv_lmk_one(cc, iv, dmreq, src + dmreq->sg_in.offset);
        kunmap_atomic(src);
    } else
        memset(iv, 0, cc->iv_size);

    return r;
}

static int crypt_iv_lmk_post(struct crypt_config *cc, u8 *iv,
                 struct dm_crypt_request *dmreq)
{
    u8 *dst;
    int r;

    if (bio_data_dir(dmreq->ctx->bio_in) == WRITE)
        return 0;

    dst = kmap_atomic(sg_page(&dmreq->sg_out));
    r = crypt_iv_lmk_one(cc, iv, dmreq, dst + dmreq->sg_out.offset);

    /* Tweak the first block of plaintext sector */
    if (!r)
        crypto_xor(dst + dmreq->sg_out.offset, iv, cc->iv_size);

    kunmap_atomic(dst);
    return r;
}

static struct crypt_iv_operations crypt_iv_plain_ops = {
    .generator = crypt_iv_plain_gen
};

static struct crypt_iv_operations crypt_iv_plain64_ops = {
    .generator = crypt_iv_plain64_gen
};

static struct crypt_iv_operations crypt_iv_essiv_ops = {
    .ctr       = crypt_iv_essiv_ctr,
    .dtr       = crypt_iv_essiv_dtr,
    .init      = crypt_iv_essiv_init,
    .wipe      = crypt_iv_essiv_wipe,
    .generator = crypt_iv_essiv_gen
};

static struct crypt_iv_operations crypt_iv_benbi_ops = {
    .ctr       = crypt_iv_benbi_ctr,
    .dtr       = crypt_iv_benbi_dtr,
    .generator = crypt_iv_benbi_gen
};

static struct crypt_iv_operations crypt_iv_null_ops = {
    .generator = crypt_iv_null_gen
};

static struct crypt_iv_operations crypt_iv_lmk_ops = {
    .ctr       = crypt_iv_lmk_ctr,
    .dtr       = crypt_iv_lmk_dtr,
    .init      = crypt_iv_lmk_init,
    .wipe      = crypt_iv_lmk_wipe,
    .generator = crypt_iv_lmk_gen,
    .post      = crypt_iv_lmk_post
};

static void crypt_convert_init(struct crypt_config *cc,
                   struct convert_context *ctx,
                   struct bio *bio_out, struct bio *bio_in,
                   sector_t sector)
{
    ctx->bio_in = bio_in;
    ctx->bio_out = bio_out;
    ctx->offset_in = 0;
    ctx->offset_out = 0;
    ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
    ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
    ctx->cc_sector = sector + cc->iv_offset;
    init_completion(&ctx->restart);
}

static struct dm_crypt_request *dmreq_of_req(struct crypt_config *cc,
                         struct ablkcipher_request *req)
{
    return (struct dm_crypt_request *)((char *)req + cc->dmreq_start);
}

static struct ablkcipher_request *req_of_dmreq(struct crypt_config *cc,
                           struct dm_crypt_request *dmreq)
{
    return (struct ablkcipher_request *)((char *)dmreq - cc->dmreq_start);
}

static u8 *iv_of_dmreq(struct crypt_config *cc,
               struct dm_crypt_request *dmreq)
{
    return (u8 *)ALIGN((unsigned long)(dmreq + 1),
        crypto_ablkcipher_alignmask(any_tfm(cc)) + 1);
}

static int crypt_convert_block(struct crypt_config *cc,
                   struct convert_context *ctx,
                   struct ablkcipher_request *req)
{
    struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
    struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
    struct dm_crypt_request *dmreq;
    u8 *iv;
    int r;

    dmreq = dmreq_of_req(cc, req);
    iv = iv_of_dmreq(cc, dmreq);

    dmreq->iv_sector = ctx->cc_sector;
    dmreq->ctx = ctx;
    sg_init_table(&dmreq->sg_in, 1);
    sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT,
            bv_in->bv_offset + ctx->offset_in);

    sg_init_table(&dmreq->sg_out, 1);
    sg_set_page(&dmreq->sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT,
            bv_out->bv_offset + ctx->offset_out);

    ctx->offset_in += 1 << SECTOR_SHIFT;
    if (ctx->offset_in >= bv_in->bv_len) {
        ctx->offset_in = 0;
        ctx->idx_in++;
    }

    ctx->offset_out += 1 << SECTOR_SHIFT;
    if (ctx->offset_out >= bv_out->bv_len) {
        ctx->offset_out = 0;
        ctx->idx_out++;
    }

    if (cc->iv_gen_ops) {
        r = cc->iv_gen_ops->generator(cc, iv, dmreq);
        if (r < 0)
            return r;
    }

    ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out,
                     1 << SECTOR_SHIFT, iv);

    if (bio_data_dir(ctx->bio_in) == WRITE)
        r = crypto_ablkcipher_encrypt(req);
    else
        r = crypto_ablkcipher_decrypt(req);

    if (!r && cc->iv_gen_ops && cc->iv_gen_ops->post)
        r = cc->iv_gen_ops->post(cc, iv, dmreq);

    return r;
}

static void kcryptd_async_done(struct crypto_async_request *async_req,
                   int error);

static void crypt_alloc_req(struct crypt_config *cc,
                struct convert_context *ctx)
{
    struct crypt_cpu *this_cc = this_crypt_config(cc);
    unsigned key_index = ctx->cc_sector & (cc->tfms_count - 1);

    if (!this_cc->req)
        this_cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);

    ablkcipher_request_set_tfm(this_cc->req, cc->tfms[key_index]);
    ablkcipher_request_set_callback(this_cc->req,
        CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
        kcryptd_async_done, dmreq_of_req(cc, this_cc->req));
}

/*
 * Encrypt / decrypt data from one bio to another one (can be the same one)
 */
static int crypt_convert(struct crypt_config *cc,
             struct convert_context *ctx)
{
    struct crypt_cpu *this_cc = this_crypt_config(cc);
    int r;

    atomic_set(&ctx->cc_pending, 1);

    while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
          ctx->idx_out < ctx->bio_out->bi_vcnt) {

        crypt_alloc_req(cc, ctx);

        atomic_inc(&ctx->cc_pending);

        r = crypt_convert_block(cc, ctx, this_cc->req);

        switch (r) {
        /* async */
        case -EBUSY:
            wait_for_completion(&ctx->restart);
            INIT_COMPLETION(ctx->restart);
            /* fall through*/
        case -EINPROGRESS:
            this_cc->req = NULL;
            ctx->cc_sector++;
            continue;

        /* sync */
        case 0:
            atomic_dec(&ctx->cc_pending);
            ctx->cc_sector++;
            cond_resched();
            continue;

        /* error */
        default:
            atomic_dec(&ctx->cc_pending);
            return r;
        }
    }

    return 0;
}

/*
 * Generate a new unfragmented bio with the given size
 * This should never violate the device limitations
 * May return a smaller bio when running out of pages, indicated by
 * *out_of_pages set to 1.
 */
static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size,
                      unsigned *out_of_pages)
{
    struct crypt_config *cc = io->cc;
    struct bio *clone;
    unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
    gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
    unsigned i, len;
    struct page *page;

    clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
    if (!clone)
        return NULL;

    clone_init(io, clone);
    *out_of_pages = 0;

    for (i = 0; i < nr_iovecs; i++) {
        page = mempool_alloc(cc->page_pool, gfp_mask);
        if (!page) {
            *out_of_pages = 1;
            break;
        }

        /*
         * If additional pages cannot be allocated without waiting,
         * return a partially-allocated bio.  The caller will then try
         * to allocate more bios while submitting this partial bio.
         */
        gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;

        len = (size > PAGE_SIZE) ? PAGE_SIZE : size;

        if (!bio_add_page(clone, page, len, 0)) {
            mempool_free(page, cc->page_pool);
            break;
        }

        size -= len;
    }

    if (!clone->bi_size) {
        bio_put(clone);
        return NULL;
    }

    return clone;
}

static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
{
    unsigned int i;
    struct bio_vec *bv;

    for (i = 0; i < clone->bi_vcnt; i++) {
        bv = bio_iovec_idx(clone, i);
        BUG_ON(!bv->bv_page);
        mempool_free(bv->bv_page, cc->page_pool);
        bv->bv_page = NULL;
    }
}

static struct dm_crypt_io *crypt_io_alloc(struct crypt_config *cc,
                      struct bio *bio, sector_t sector)
{
    struct dm_crypt_io *io;

    io = mempool_alloc(cc->io_pool, GFP_NOIO);
    io->cc = cc;
    io->base_bio = bio;
    io->sector = sector;
    io->error = 0;
    io->base_io = NULL;
    atomic_set(&io->io_pending, 0);

    return io;
}

static void crypt_inc_pending(struct dm_crypt_io *io)
{
    atomic_inc(&io->io_pending);
}

/*
 * One of the bios was finished. Check for completion of
 * the whole request and correctly clean up the buffer.
 * If base_io is set, wait for the last fragment to complete.
 */
static void crypt_dec_pending(struct dm_crypt_io *io)
{
    struct crypt_config *cc = io->cc;
    struct bio *base_bio = io->base_bio;
    struct dm_crypt_io *base_io = io->base_io;
    int error = io->error;

    if (!atomic_dec_and_test(&io->io_pending))
        return;

    mempool_free(io, cc->io_pool);

    if (likely(!base_io))
        bio_endio(base_bio, error);
    else {
        if (error && !base_io->error)
            base_io->error = error;
        crypt_dec_pending(base_io);
    }
}

/*
 * kcryptd/kcryptd_io:
 *
 * Needed because it would be very unwise to do decryption in an
 * interrupt context.
 *
 * kcryptd performs the actual encryption or decryption.
 *
 * kcryptd_io performs the IO submission.
 *
 * They must be separated as otherwise the final stages could be
 * starved by new requests which can block in the first stages due
 * to memory allocation.
 *
 * The work is done per CPU global for all dm-crypt instances.
 * They should not depend on each other and do not block.
 */
static void crypt_endio(struct bio *clone, int error)
{
    struct dm_crypt_io *io = clone->bi_private;
    struct crypt_config *cc = io->cc;
    unsigned rw = bio_data_dir(clone);

    if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
        error = -EIO;

    /*
     * free the processed pages
     */
    if (rw == WRITE)
        crypt_free_buffer_pages(cc, clone);

    bio_put(clone);

    if (rw == READ && !error) {
        kcryptd_queue_crypt(io);
        return;
    }

    if (unlikely(error))
        io->error = error;

    crypt_dec_pending(io);
}

static void clone_init(struct dm_crypt_io *io, struct bio *clone)
{
    struct crypt_config *cc = io->cc;

    clone->bi_private = io;
    clone->bi_end_io  = crypt_endio;
    clone->bi_bdev    = cc->dev->bdev;
    clone->bi_rw      = io->base_bio->bi_rw;
}

static int kcryptd_io_read(struct dm_crypt_io *io, gfp_t gfp)
{
    struct crypt_config *cc = io->cc;
    struct bio *base_bio = io->base_bio;
    struct bio *clone;

    /*
     * The block layer might modify the bvec array, so always
     * copy the required bvecs because we need the original
     * one in order to decrypt the whole bio data *afterwards*.
     */
    clone = bio_clone_bioset(base_bio, gfp, cc->bs);
    if (!clone)
        return 1;

    crypt_inc_pending(io);

    clone_init(io, clone);
    clone->bi_sector = cc->start + io->sector;

    generic_make_request(clone);
    return 0;
}

static void kcryptd_io_write(struct dm_crypt_io *io)
{
    struct bio *clone = io->ctx.bio_out;
    generic_make_request(clone);
}

static void kcryptd_io(struct work_struct *work)
{
    struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);

    if (bio_data_dir(io->base_bio) == READ) {
        crypt_inc_pending(io);
        if (kcryptd_io_read(io, GFP_NOIO))
            io->error = -ENOMEM;
        crypt_dec_pending(io);
    } else
        kcryptd_io_write(io);
}

static void kcryptd_queue_io(struct dm_crypt_io *io)
{
    struct crypt_config *cc = io->cc;

    INIT_WORK(&io->work, kcryptd_io);
    queue_work(cc->io_queue, &io->work);
}

static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int async)
{
    struct bio *clone = io->ctx.bio_out;
    struct crypt_config *cc = io->cc;

    if (unlikely(io->error < 0)) {
        crypt_free_buffer_pages(cc, clone);
        bio_put(clone);
        crypt_dec_pending(io);
        return;
    }

    /* crypt_convert should have filled the clone bio */
    BUG_ON(io->ctx.idx_out < clone->bi_vcnt);

    clone->bi_sector = cc->start + io->sector;

    if (async)
        kcryptd_queue_io(io);
    else
        generic_make_request(clone);
}

static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
{
    struct crypt_config *cc = io->cc;
    struct bio *clone;
    struct dm_crypt_io *new_io;
    int crypt_finished;
    unsigned out_of_pages = 0;
    unsigned remaining = io->base_bio->bi_size;
    sector_t sector = io->sector;
    int r;

    /*
     * Prevent io from disappearing until this function completes.
     */
    crypt_inc_pending(io);
    crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector);

    /*
     * The allocated buffers can be smaller than the whole bio,
     * so repeat the whole process until all the data can be handled.
     */
    while (remaining) {
        clone = crypt_alloc_buffer(io, remaining, &out_of_pages);
        if (unlikely(!clone)) {
            io->error = -ENOMEM;
            break;
        }

        io->ctx.bio_out = clone;
        io->ctx.idx_out = 0;

        remaining -= clone->bi_size;
        sector += bio_sectors(clone);

        crypt_inc_pending(io);

        r = crypt_convert(cc, &io->ctx);
        if (r < 0)
            io->error = -EIO;

        crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending);

        /* Encryption was already finished, submit io now */
        if (crypt_finished) {
            kcryptd_crypt_write_io_submit(io, 0);

            /*
             * If there was an error, do not try next fragments.
             * For async, error is processed in async handler.
             */
            if (unlikely(r < 0))
                break;

            io->sector = sector;
        }

        /*
         * Out of memory -> run queues
         * But don't wait if split was due to the io size restriction
         */
        if (unlikely(out_of_pages))
            congestion_wait(BLK_RW_ASYNC, HZ/100);

        /*
         * With async crypto it is unsafe to share the crypto context
         * between fragments, so switch to a new dm_crypt_io structure.
         */
        if (unlikely(!crypt_finished && remaining)) {
            new_io = crypt_io_alloc(io->cc, io->base_bio,
                        sector);
            crypt_inc_pending(new_io);
            crypt_convert_init(cc, &new_io->ctx, NULL,
                       io->base_bio, sector);
            new_io->ctx.idx_in = io->ctx.idx_in;
            new_io->ctx.offset_in = io->ctx.offset_in;

            /*
             * Fragments after the first use the base_io
             * pending count.
             */
            if (!io->base_io)
                new_io->base_io = io;
            else {
                new_io->base_io = io->base_io;
                crypt_inc_pending(io->base_io);
                crypt_dec_pending(io);
            }

            io = new_io;
        }
    }

    crypt_dec_pending(io);
}

static void kcryptd_crypt_read_done(struct dm_crypt_io *io)
{
    crypt_dec_pending(io);
}

static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
{
    struct crypt_config *cc = io->cc;
    int r = 0;

    crypt_inc_pending(io);

    crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
               io->sector);

    r = crypt_convert(cc, &io->ctx);
    if (r < 0)
        io->error = -EIO;

    if (atomic_dec_and_test(&io->ctx.cc_pending))
        kcryptd_crypt_read_done(io);

    crypt_dec_pending(io);
}

static void kcryptd_async_done(struct crypto_async_request *async_req,
                   int error)
{
    struct dm_crypt_request *dmreq = async_req->data;
    struct convert_context *ctx = dmreq->ctx;
    struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
    struct crypt_config *cc = io->cc;

    if (error == -EINPROGRESS) {
        complete(&ctx->restart);
        return;
    }

    if (!error && cc->iv_gen_ops && cc->iv_gen_ops->post)
        error = cc->iv_gen_ops->post(cc, iv_of_dmreq(cc, dmreq), dmreq);

    if (error < 0)
        io->error = -EIO;

    mempool_free(req_of_dmreq(cc, dmreq), cc->req_pool);

    if (!atomic_dec_and_test(&ctx->cc_pending))
        return;

    if (bio_data_dir(io->base_bio) == READ)
        kcryptd_crypt_read_done(io);
    else
        kcryptd_crypt_write_io_submit(io, 1);
}

static void kcryptd_crypt(struct work_struct *work)
{
    struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);

    if (bio_data_dir(io->base_bio) == READ)
        kcryptd_crypt_read_convert(io);
    else
        kcryptd_crypt_write_convert(io);
}

static void kcryptd_queue_crypt(struct dm_crypt_io *io)
{
    struct crypt_config *cc = io->cc;

    INIT_WORK(&io->work, kcryptd_crypt);
    queue_work(cc->crypt_queue, &io->work);
}

/*
 * Decode key from its hex representation
 */
static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
{
    char buffer[3];
    unsigned int i;

    buffer[2] = '\0';

    for (i = 0; i < size; i++) {
        buffer[0] = *hex++;
        buffer[1] = *hex++;

        if (kstrtou8(buffer, 16, &key[i]))
            return -EINVAL;
    }

    if (*hex != '\0')
        return -EINVAL;

    return 0;
}

/*
 * Encode key into its hex representation
 */
static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
{
    unsigned int i;

    for (i = 0; i < size; i++) {
        sprintf(hex, "%02x", *key);
        hex += 2;
        key++;
    }
}

static void crypt_free_tfms(struct crypt_config *cc)
{
    unsigned i;

    if (!cc->tfms)
        return;

    for (i = 0; i < cc->tfms_count; i++)
        if (cc->tfms[i] && !IS_ERR(cc->tfms[i])) {
            crypto_free_ablkcipher(cc->tfms[i]);
            cc->tfms[i] = NULL;
        }

    kfree(cc->tfms);
    cc->tfms = NULL;
}

static int crypt_alloc_tfms(struct crypt_config *cc, char *ciphermode)
{
    unsigned i;
    int err;

    cc->tfms = kmalloc(cc->tfms_count * sizeof(struct crypto_ablkcipher *),
               GFP_KERNEL);
    if (!cc->tfms)
        return -ENOMEM;

    for (i = 0; i < cc->tfms_count; i++) {
        cc->tfms[i] = crypto_alloc_ablkcipher(ciphermode, 0, 0);
        if (IS_ERR(cc->tfms[i])) {
            err = PTR_ERR(cc->tfms[i]);
            crypt_free_tfms(cc);
            return err;
        }
    }

    return 0;
}

static int crypt_setkey_allcpus(struct crypt_config *cc)
{
    unsigned subkey_size = cc->key_size >> ilog2(cc->tfms_count);
    int err = 0, i, r;

    for (i = 0; i < cc->tfms_count; i++) {
        r = crypto_ablkcipher_setkey(cc->tfms[i],
                         cc->key + (i * subkey_size),
                         subkey_size);
        if (r)
            err = r;
    }

    return err;
}

static int crypt_set_key(struct crypt_config *cc, char *key)
{
    int r = -EINVAL;
    int key_string_len = strlen(key);

    /* The key size may not be changed. */
    if (cc->key_size != (key_string_len >> 1))
        goto out;

    /* Hyphen (which gives a key_size of zero) means there is no key. */
    if (!cc->key_size && strcmp(key, "-"))
        goto out;

    if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)
        goto out;

    set_bit(DM_CRYPT_KEY_VALID, &cc->flags);

    r = crypt_setkey_allcpus(cc);

out:
    /* Hex key string not needed after here, so wipe it. */
    memset(key, '0', key_string_len);

    return r;
}

static int crypt_wipe_key(struct crypt_config *cc)
{
    clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
    memset(&cc->key, 0, cc->key_size * sizeof(u8));

    return crypt_setkey_allcpus(cc);
}

static void crypt_dtr(struct dm_target *ti)
{
    struct crypt_config *cc = ti->private;
    struct crypt_cpu *cpu_cc;
    int cpu;

    ti->private = NULL;

    if (!cc)
        return;

    if (cc->io_queue)
        destroy_workqueue(cc->io_queue);
    if (cc->crypt_queue)
        destroy_workqueue(cc->crypt_queue);

    if (cc->cpu)
        for_each_possible_cpu(cpu) {
            cpu_cc = per_cpu_ptr(cc->cpu, cpu);
            if (cpu_cc->req)
                mempool_free(cpu_cc->req, cc->req_pool);
        }

    crypt_free_tfms(cc);

    if (cc->bs)
        bioset_free(cc->bs);

    if (cc->page_pool)
        mempool_destroy(cc->page_pool);
    if (cc->req_pool)
        mempool_destroy(cc->req_pool);
    if (cc->io_pool)
        mempool_destroy(cc->io_pool);

    if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
        cc->iv_gen_ops->dtr(cc);

    if (cc->dev)
        dm_put_device(ti, cc->dev);

    if (cc->cpu)
        free_percpu(cc->cpu);

    kzfree(cc->cipher);
    kzfree(cc->cipher_string);

    /* Must zero key material before freeing */
    kzfree(cc);
}

static int crypt_ctr_cipher(struct dm_target *ti,
                char *cipher_in, char *key)
{
    struct crypt_config *cc = ti->private;
    char *tmp, *cipher, *chainmode, *ivmode, *ivopts, *keycount;
    char *cipher_api = NULL;
    int ret = -EINVAL;
    char dummy;

    /* Convert to crypto api definition? */
    if (strchr(cipher_in, '(')) {
        ti->error = "Bad cipher specification";
        return -EINVAL;
    }

    cc->cipher_string = kstrdup(cipher_in, GFP_KERNEL);
    if (!cc->cipher_string)
        goto bad_mem;

    /*
     * Legacy dm-crypt cipher specification
     * cipher[:keycount]-mode-iv:ivopts
     */
    tmp = cipher_in;
    keycount = strsep(&tmp, "-");
    cipher = strsep(&keycount, ":");

    if (!keycount)
        cc->tfms_count = 1;
    else if (sscanf(keycount, "%u%c", &cc->tfms_count, &dummy) != 1 ||
         !is_power_of_2(cc->tfms_count)) {
        ti->error = "Bad cipher key count specification";
        return -EINVAL;
    }
    cc->key_parts = cc->tfms_count;

    cc->cipher = kstrdup(cipher, GFP_KERNEL);
    if (!cc->cipher)
        goto bad_mem;

    chainmode = strsep(&tmp, "-");
    ivopts = strsep(&tmp, "-");
    ivmode = strsep(&ivopts, ":");

    if (tmp)
        DMWARN("Ignoring unexpected additional cipher options");

    cc->cpu = __alloc_percpu(sizeof(*(cc->cpu)),
                 __alignof__(struct crypt_cpu));
    if (!cc->cpu) {
        ti->error = "Cannot allocate per cpu state";
        goto bad_mem;
    }

    /*
     * For compatibility with the original dm-crypt mapping format, if
     * only the cipher name is supplied, use cbc-plain.
     */
    if (!chainmode || (!strcmp(chainmode, "plain") && !ivmode)) {
        chainmode = "cbc";
        ivmode = "plain";
    }

    if (strcmp(chainmode, "ecb") && !ivmode) {
        ti->error = "IV mechanism required";
        return -EINVAL;
    }

    cipher_api = kmalloc(CRYPTO_MAX_ALG_NAME, GFP_KERNEL);
    if (!cipher_api)
        goto bad_mem;

    ret = snprintf(cipher_api, CRYPTO_MAX_ALG_NAME,
               "%s(%s)", chainmode, cipher);
    if (ret < 0) {
        kfree(cipher_api);
        goto bad_mem;
    }

    /* Allocate cipher */
    ret = crypt_alloc_tfms(cc, cipher_api);
    if (ret < 0) {
        ti->error = "Error allocating crypto tfm";
        goto bad;
    }

    /* Initialize and set key */
    ret = crypt_set_key(cc, key);
    if (ret < 0) {
        ti->error = "Error decoding and setting key";
        goto bad;
    }

    /* Initialize IV */
    cc->iv_size = crypto_ablkcipher_ivsize(any_tfm(cc));
    if (cc->iv_size)
        /* at least a 64 bit sector number should fit in our buffer */
        cc->iv_size = max(cc->iv_size,
                  (unsigned int)(sizeof(u64) / sizeof(u8)));
    else if (ivmode) {
        DMWARN("Selected cipher does not support IVs");
        ivmode = NULL;
    }

    /* Choose ivmode, see comments at iv code. */
    if (ivmode == NULL)
        cc->iv_gen_ops = NULL;
    else if (strcmp(ivmode, "plain") == 0)
        cc->iv_gen_ops = &crypt_iv_plain_ops;
    else if (strcmp(ivmode, "plain64") == 0)
        cc->iv_gen_ops = &crypt_iv_plain64_ops;
    else if (strcmp(ivmode, "essiv") == 0)
        cc->iv_gen_ops = &crypt_iv_essiv_ops;
    else if (strcmp(ivmode, "benbi") == 0)
        cc->iv_gen_ops = &crypt_iv_benbi_ops;
    else if (strcmp(ivmode, "null") == 0)
        cc->iv_gen_ops = &crypt_iv_null_ops;
    else if (strcmp(ivmode, "lmk") == 0) {
        cc->iv_gen_ops = &crypt_iv_lmk_ops;
        /* Version 2 and 3 is recognised according
         * to length of provided multi-key string.
         * If present (version 3), last key is used as IV seed.
         */
        if (cc->key_size % cc->key_parts)
            cc->key_parts++;
    } else {
        ret = -EINVAL;
        ti->error = "Invalid IV mode";
        goto bad;
    }

    /* Allocate IV */
    if (cc->iv_gen_ops && cc->iv_gen_ops->ctr) {
        ret = cc->iv_gen_ops->ctr(cc, ti, ivopts);
        if (ret < 0) {
            ti->error = "Error creating IV";
            goto bad;
        }
    }

    /* Initialize IV (set keys for ESSIV etc) */
    if (cc->iv_gen_ops && cc->iv_gen_ops->init) {
        ret = cc->iv_gen_ops->init(cc);
        if (ret < 0) {
            ti->error = "Error initialising IV";
            goto bad;
        }
    }

    ret = 0;
bad:
    kfree(cipher_api);
    return ret;

bad_mem:
    ti->error = "Cannot allocate cipher strings";
    return -ENOMEM;
}

/*
 * Construct an encryption mapping:
 * <cipher> <key> <iv_offset> <dev_path> <start>
 */
static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
    struct crypt_config *cc;
    unsigned int key_size, opt_params;
    unsigned long long tmpll;
    int ret;
    struct dm_arg_set as;
    const char *opt_string;
    char dummy;

    static struct dm_arg _args[] = {
        {0, 1, "Invalid number of feature args"},
    };

    if (argc < 5) {
        ti->error = "Not enough arguments";
        return -EINVAL;
    }

    key_size = strlen(argv[1]) >> 1;

    cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
    if (!cc) {
        ti->error = "Cannot allocate encryption context";
        return -ENOMEM;
    }
    cc->key_size = key_size;

    ti->private = cc;
    ret = crypt_ctr_cipher(ti, argv[0], argv[1]);
    if (ret < 0)
        goto bad;

    ret = -ENOMEM;
    cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
    if (!cc->io_pool) {
        ti->error = "Cannot allocate crypt io mempool";
        goto bad;
    }

    cc->dmreq_start = sizeof(struct ablkcipher_request);
    cc->dmreq_start += crypto_ablkcipher_reqsize(any_tfm(cc));
    cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());
    cc->dmreq_start += crypto_ablkcipher_alignmask(any_tfm(cc)) &
               ~(crypto_tfm_ctx_alignment() - 1);

    cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
            sizeof(struct dm_crypt_request) + cc->iv_size);
    if (!cc->req_pool) {
        ti->error = "Cannot allocate crypt request mempool";
        goto bad;
    }

    cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
    if (!cc->page_pool) {
        ti->error = "Cannot allocate page mempool";
        goto bad;
    }

    cc->bs = bioset_create(MIN_IOS, 0);
    if (!cc->bs) {
        ti->error = "Cannot allocate crypt bioset";
        goto bad;
    }

    ret = -EINVAL;
    if (sscanf(argv[2], "%llu%c", &tmpll, &dummy) != 1) {
        ti->error = "Invalid iv_offset sector";
        goto bad;
    }
    cc->iv_offset = tmpll;

    if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &cc->dev)) {
        ti->error = "Device lookup failed";
        goto bad;
    }

    if (sscanf(argv[4], "%llu%c", &tmpll, &dummy) != 1) {
        ti->error = "Invalid device sector";
        goto bad;
    }
    cc->start = tmpll;

    argv += 5;
    argc -= 5;

    /* Optional parameters */
    if (argc) {
        as.argc = argc;
        as.argv = argv;

        ret = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
        if (ret)
            goto bad;

        opt_string = dm_shift_arg(&as);

        if (opt_params == 1 && opt_string &&
            !strcasecmp(opt_string, "allow_discards"))
            ti->num_discard_requests = 1;
        else if (opt_params) {
            ret = -EINVAL;
            ti->error = "Invalid feature arguments";
            goto bad;
        }
    }

    ret = -ENOMEM;
    cc->io_queue = alloc_workqueue("kcryptd_io",
                       WQ_NON_REENTRANT|
                       WQ_MEM_RECLAIM,
                       1);
    if (!cc->io_queue) {
        ti->error = "Couldn't create kcryptd io queue";
        goto bad;
    }

    cc->crypt_queue = alloc_workqueue("kcryptd",
                      WQ_NON_REENTRANT|
                      WQ_CPU_INTENSIVE|
                      WQ_MEM_RECLAIM,
                      1);
    if (!cc->crypt_queue) {
        ti->error = "Couldn't create kcryptd queue";
        goto bad;
    }

    ti->num_flush_requests = 1;
    ti->discard_zeroes_data_unsupported = true;

    return 0;

bad:
    crypt_dtr(ti);
    return ret;
}

static int crypt_map(struct dm_target *ti, struct bio *bio,
             union map_info *map_context)
{
    struct dm_crypt_io *io;
    struct crypt_config *cc = ti->private;

    /*
     * If bio is REQ_FLUSH or REQ_DISCARD, just bypass crypt queues.
     * - for REQ_FLUSH device-mapper core ensures that no IO is in-flight
     * - for REQ_DISCARD caller must use flush if IO ordering matters
     */
    if (unlikely(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD))) {
        bio->bi_bdev = cc->dev->bdev;
        if (bio_sectors(bio))
            bio->bi_sector = cc->start + dm_target_offset(ti, bio->bi_sector);
        return DM_MAPIO_REMAPPED;
    }

    io = crypt_io_alloc(cc, bio, dm_target_offset(ti, bio->bi_sector));

    if (bio_data_dir(io->base_bio) == READ) {
        if (kcryptd_io_read(io, GFP_NOWAIT))
            kcryptd_queue_io(io);
    } else
        kcryptd_queue_crypt(io);

    return DM_MAPIO_SUBMITTED;
}

static int crypt_status(struct dm_target *ti, status_type_t type,
            unsigned status_flags, char *result, unsigned maxlen)
{
    struct crypt_config *cc = ti->private;
    unsigned int sz = 0;

    switch (type) {
    case STATUSTYPE_INFO:
        result[0] = '\0';
        break;

    case STATUSTYPE_TABLE:
        DMEMIT("%s ", cc->cipher_string);

        if (cc->key_size > 0) {
            if ((maxlen - sz) < ((cc->key_size << 1) + 1))
                return -ENOMEM;

            crypt_encode_key(result + sz, cc->key, cc->key_size);
            sz += cc->key_size << 1;
        } else {
            if (sz >= maxlen)
                return -ENOMEM;
            result[sz++] = '-';
        }

        DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
                cc->dev->name, (unsigned long long)cc->start);

        if (ti->num_discard_requests)
            DMEMIT(" 1 allow_discards");

        break;
    }
    return 0;
}

static void crypt_postsuspend(struct dm_target *ti)
{
    struct crypt_config *cc = ti->private;

    set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
}

static int crypt_preresume(struct dm_target *ti)
{
    struct crypt_config *cc = ti->private;

    if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
        DMERR("aborting resume - crypt key is not set.");
        return -EAGAIN;
    }

    return 0;
}

static void crypt_resume(struct dm_target *ti)
{
    struct crypt_config *cc = ti->private;

    clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
}

/* Message interface
 *  key set <key>
 *  key wipe
 */
static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
{
    struct crypt_config *cc = ti->private;
    int ret = -EINVAL;

    if (argc < 2)
        goto error;

    if (!strcasecmp(argv[0], "key")) {
        if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
            DMWARN("not suspended during key manipulation.");
            return -EINVAL;
        }
        if (argc == 3 && !strcasecmp(argv[1], "set")) {
            ret = crypt_set_key(cc, argv[2]);
            if (ret)
                return ret;
            if (cc->iv_gen_ops && cc->iv_gen_ops->init)
                ret = cc->iv_gen_ops->init(cc);
            return ret;
        }
        if (argc == 2 && !strcasecmp(argv[1], "wipe")) {
            if (cc->iv_gen_ops && cc->iv_gen_ops->wipe) {
                ret = cc->iv_gen_ops->wipe(cc);
                if (ret)
                    return ret;
            }
            return crypt_wipe_key(cc);
        }
    }

error:
    DMWARN("unrecognised message received.");
    return -EINVAL;
}

static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
               struct bio_vec *biovec, int max_size)
{
    struct crypt_config *cc = ti->private;
    struct request_queue *q = bdev_get_queue(cc->dev->bdev);

    if (!q->merge_bvec_fn)
        return max_size;

    bvm->bi_bdev = cc->dev->bdev;
    bvm->bi_sector = cc->start + dm_target_offset(ti, bvm->bi_sector);

    return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
}

static int crypt_iterate_devices(struct dm_target *ti,
                 iterate_devices_callout_fn fn, void *data)
{
    struct crypt_config *cc = ti->private;

    return fn(ti, cc->dev, cc->start, ti->len, data);
}

static struct target_type crypt_target = {
    .name   = "crypt",
    .version = {1, 11, 0},
    .module = THIS_MODULE,
    .ctr    = crypt_ctr,
    .dtr    = crypt_dtr,
    .map    = crypt_map,
    .status = crypt_status,
    .postsuspend = crypt_postsuspend,
    .preresume = crypt_preresume,
    .resume = crypt_resume,
    .message = crypt_message,
    .merge  = crypt_merge,
    .iterate_devices = crypt_iterate_devices,
};

static int __init dm_crypt_init(void)
{
    int r;

    _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
    if (!_crypt_io_pool)
        return -ENOMEM;

    r = dm_register_target(&crypt_target);
    if (r < 0) {
        DMERR("register failed %d", r);
        kmem_cache_destroy(_crypt_io_pool);
    }

    return r;
}

static void __exit dm_crypt_exit(void)
{
    dm_unregister_target(&crypt_target);
    kmem_cache_destroy(_crypt_io_pool);
}

module_init(dm_crypt_init);
module_exit(dm_crypt_exit);

MODULE_AUTHOR("Christophe Saout <[email protected]>");
MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
MODULE_LICENSE("GPL");